Large capacity bulldozer



Feb. 25, 1964 D. E COBB LARGE CAPACITY BULLDOZER 3 Sheets-Sheet 1 Filed April 2, 1962 mm /M M fi v R w I I j m rw 1 .E 2 9 O Q ME Q o m E ..4.////fl/ E W N Q D 419 i B MN m H I I? IE h Feb. 25, 1964 D. E. COBB 3,121,964

LARGE CAPACITY BULLDOZER Filed April 2, 1962 3 Sheets-Sheet 2 INVENTOR. Dau/vm ECQBB ATTORNEYS Feb. 25, 1964 D. E. COBB LARGE CAPACITY BULLDOZER 3 Sheets-Sheet 3 Filed April 2, 1962 INVENTQR. DELW|N E. Cogs AT T O RNEYS United States Patent 3,121,964 LARGE CAPACHTY BULLDUZER Delwin E. Cobb, Peoria, 111., assignor to Caterpillar Tractor (10., Peoria, ill, a corporation of California Filed Apr. 2, 1962, Ser- No. 184,055 3 Claims. (Cl. 37-143) The present invention relates to bulldozers and particularly to a bulldozer designed to move a relatively large quantity of earth with relatively low effort and high speed.

Bulldozers are commonly used for stock piling, hopper loading and general clean-up work. Their capacity, however, is relatively small compared to other forms of earthrnoving equipment so that the distance over which dirt or other materials may be moved economically is limited. Consequently, the versatility of the ordinary bulldozer is limited and it is often necessary to employ a bulldozer in the loosening or first movement of earth and then another piece of equipment for conveying the earth to a desired location.

It is the object of the present invention to provide a bulldozer having substantially greater capacity for its size than an ordinary bulldozer and with which earth can be accumulated with relative ease and economically transported over distances where the use of conventional bulldozers is not economical.

Further and more specific objects and advantages of the present invention and the manner in which it is carried into practice are made apparent in the following specification wherein reference is made to the accompanying drawings.

In the drawings:

FIG. 1 is a view in side elevation of a bulldozer embodying the present invention showing the forward end of the tractor by means of which it is manipulated and showing the bulldozer in vertical section;

FIG. 2 is a perspective view of the bulldozer shown in PEG. 1;

FIG. 3 is a view in side elevation showing a modified form of the bulldozer;

*FIG. 4 is a schematic view showing the manner in which earth is moved with a conventional bulldozer, and

P16. 5 is a similar View showing the improved manner in which earth is moved with the bulldozer of the present invention.

In FIG. 1, a bulldozer generally indicated at Ill is shown as carried at the forward ends of a pair of push arms, one of which is shown at 11 as pivotally connected at 12 to a tractor, the forward portion of which is shown at 13. The entire bulldozer may be raised and low ered with respect to the tractor in a conventional manner by a pair of lift jacks, one of which is shown at 14, and the bulldozer may be pitched forwardly or rearwardly with respect to the ground or tilted laterally by means of a pair of pitch and tilt jacks, one of which is shown at 15, all in a well known manner. 2

The bulldozer itself comprises a moldboard 16 similar to that of conventional bulldozers. In accordance with the present invention, a pair of end walls 1'7 extend forwardly from the opposite ends of the moldboard 16 and these end walls may be reinforced as by plates shown at 18 welded to them and tapered outwardly and downwardly with intermediate bracing, not shown. A cutting edge 20 is supported at ground level between the forward lower edges of the end walls 17 and preferably reinforced by a strut 21 extending between the moldboard and the rear of a beam 22 to which removable hardened cutting plates of the cutting edge are secured. Since, during a bulldozing operation earth encountered by the cutting edge 20 will be raised and fall into the bottomless opening between the end walls 17 and mcldbo-ard 16 "an extension, which may be in grid form as shown at 23, is secured to and extends upwardly from the upper edge of the moldboard to prevent excessive earth or other material from falling over the moldboard when a large load is being moved. The lower edge of the moldboard is provided with a skid plate as shown at 24 in FIG. 1 for a purpose presently to be described.

In the operation of collecting earth with the bulldozer of the present invention, liit jacks 14 are placed in a float condition such that the opposite ends of the jacks are hydraulically interconnected by positioning of conventio-nal control means (not shown), and the bulldozer is pitched forwardly from the position shown in FIG. 1 by extension of the jacks 15 through hydraulic means, not shown, but of conventional and well known construction. With this forward pitch, the cutting edge 20 enters the earth to any desired depth and hits it column of earth which is deposited into the box-like space between the end walls 17. As the blade reaches the desired cutting depth, jacks 15 are retracted until the lower edge of cutting edge 2t) and skid plate 24 are substantially level in order that the blade may be advanced through the soil at the selected cutting depth. When the space is loaded to its capacity, jacks 15 are further retracted to raise cutting edge 26 in relation to skid plate 24, thus permitting the blade to rise to the surface of the ground for the purpose of transporting the contents of the bulldozer to the place where it is to be discharged.

For discharging the load, the lift jacks 14 are retracted to raise the entire bulldozer structure about its pivotal connection 12 with the tractor and permit the earth transported thereby to escape through its open bottom and under the skid plate 24. The skid plate 24 may, of course, be employed to level the earth as it is discharged and depth of fill created by the discharge may be regulated by manipulation of the lift jacks 14. Superior and more easily controlled leveling is alfected because earth is prevented from spilling past the ends of the moldbolard by the end walls 17.

The design and method of operation as heretofore described is desirable for use on machines affording good visibility of the blade, or in materials where penetration is particularly difficult or the smoothness of the finished surface is important. When the bulldozer is employed on machines which obstruct the operators view such that it is difficult to detect the position of the blade, more eificient operation is achieved by positioning the blade in a substantially level condition and using the lift jacks to regulate the depth of cut. The design of FIG. 1 may cause some difficulty when operated in this manner in some types of soils since the large bearing surface provided by skid plate 24 may interfere with proper penetration of the blade in the ground. f

FIG. 3 discloses a modified design which embodies the features of the invention as set forth in the objects and yet permitting efficient operation in the manner last described. Since the major portion of the design of FIG. 3 is substantially like that of FIG. 1, only the modifications will be described with similar reference characters suffixed by the letter a designating common parts. The skid plate 24 of FIG. 1 has been replaced by a lilardened, replaceable cutting edge 30 which is secured in any convenient manner to the lower forward edge of the moldboard 16a. The strut 21 (FIG. 1) has been eliminated since the materials to be Worked with this modified design do not impose loads of sufficient magnitude on the cutting edge Zila to require intermediate bracing. A single hydraulic tilt jack 15a is provided at only one side of the blade with a manually adjustable tilt brace 32 replacing the second tilt jack of FIG. 1. This permits the blade to be hydraulically tilted in a lateral direction a but does not provide hydraulic fore and aft pitch of the blade.

Filling of the blade is accomplished by extending the lift jacks 14a to lower the blade lea with respect to tne ground as the machine advances so that cutting edges 29:: and 3d are forced into the earth to the desired depth. The lift jacks are then hydrauiically locked in this position and the blade is moved forwardly causing the earth to flow over the cutting edge 26a and into the space between the end walls 17a. When the space is filled to its capacity the jacks 14a are retracted to raise blade lea to the surface of the ground to transport its contents to the area where it is to be discharged. The load is discharged by further retraction of jacks 14a to raise the blade and permit the earth to escape through its open bottom. The material is spread and leveled as it is discharged in a manner similar to that described in connection with FIG. 1.

The above described method of operation transfers the weight of the blade and the material supported thereon, as well as the downward force created by the digging action of the cutting edge, through the lift jacks 14a to the tractor thus increasing the traction of the machine. The resulting increase in tractive effort permits the blade to be advanced at a higher speed to decrease the time required to fill the blade and improve the overall elrioiency of a machine of this type.

The difference in the manner of operation of the bulldozer of the present invention and that of conventional bulldozers and the reason that its capacity is greater with little or no increase in effort by the tractor with which it is associated is made apparent in FIGS. 3 and 4 of the drawings schematically illustrating the manner in which earth is collected and moved. FIG. 3 shows the conventional bulldozer cutting and advancing the earth with the cutting edge of the bulldozer severing a column of earth 26 which passes upwardly against the forward face of the moldboard against the pressure of earth above it and before it. FIG. 4 shows the bulldozer 16 of the present invention with its cutting edge severing a comparable column of earth 27 which moves freely upwardly over the main body of earth already contained between the end walls and in front of the moldboard. This upward movement is induced by the angle of the cutting blade L and is not opposed by earth already deposited in front of the moldboard. The resistance to forward movement of bulldozer constructed in accordance with the present invention as compared with a conventional bulldozer of comparable size enables the cutting and moving of more than double the amount of earth with the same effort on the part of the tractor, thus very much greater loads may be received by the bulldozer making it economical to move these loads a substantially greater distance than is economical with conventional bulldozers. This not only reduces the overall cost of cutting and moving earth but increases the versatility of the bulldozer to the point where a single piece of equipment may often times be employed economically where additional equipment would otherwise be necessary.

I claim:

1. A bulldozer mounted on push arms forwardly of a tractor with means for raising and lowering the forward ends of the arms and means to effect forward pitching of the bulldozer with respect to the arms comprising a moldboard, end walls extending forwardly from opposite ends of the moldboard, and a cutting edge extending between the lower forward portions only of the end walls leaving an open bottomless area between the cutting edge, the moldbo ard and the two end Walls whereby material gathered by the cutting edge in forward movement will be deposited in the bottomless box-like structure formed by the moldboard end walls and cutting edge.

2. The combination of claim 1 in which a skid plate is disposed beneath the moldboard.

3. The combination of claim 1 with at least one strut extending between the moldboard land the cutting edge intermediate the end walls.

References Cited in the file of this patent UNITED STATES PATENTS 891,916 Defrees June 30, 1908 1,453,540 Beach et a1. May 1, 1923 1,682,137 McMillan Aug. 28, 1928 1,693,353 Slavin Nov. 27, 1928 1,891,288 Shanor Dec. 20, 1932 2,213,635 Miller et a1. Sept. 3, 1940 2,812,595 Drott Nov. 12, 1957 

1. A BULLDOZER MOUNTED ON PUSH ARMS FORWARDLY OF A TRACTOR WITH MEANS FOR RAISING AND LOWERING THE FORWARD ENDS OF THE ARMS AND MEANS TO EFFECT FORWARD PITCHING OF THE BULLDOZER WITH RESPECT TO THE ARMS COMPRISING A MOLDBOARD, END WALLS EXTENDING FORWARDLY FROM OPPOSITE ENDS OF THE MOLDBOARD, AND A CUTTING EDGE EXTENDING BETWEEN THE LOWER FORWARD PORTIONS ONLY OF THE END WALLS LEAVING AN OPEN BOTTOMLESS AREA BETWEEN THE CUTTING EDGE, THE MOLDBOARD AND THE TWO END WALLS WHEREBY MATERIAL GATHERED BY THE CUTTING EDGE IN FORWARD MOVEMENT WILL 